21mm And Distortion

[MCTuomey]

The best way out is to get your taking position right so that the camera can be level and the framing is correct. That way there is simply no need for a view camera. Of course that is not always feasible but is often overlooked when it is. It's just too easy to point the camera up or down rather than move yourself to the optimum position (which might include getting yourself into a middle floor of a building opposite).

Apologies if this is OT, but I found your post interesting.

What happens when you've got the camera level and the framing "correct" and you find yourself with a whole lot of street/parking lot/other in the foreground that's unwanted? You can change lenses. You can crop later. Or, if you have movements you can shift upward and eliminate the unwanted foreground in a few seconds.

Ok, one doesn't "need" a view camera. Just saying there's very often a lot of value in a view camera's movements which is why I like my 35mm T-S lenses a lot.

 

[wjlapier]

Oh hello William
its exactly that 'Look' that made Me fall for a 21 SA...the Exaggerated sense of Proportion

Interesting how the buildings are leaning to the left on the left side of the picture and as you look to the right the buildings by the park are leaning to the right.

Looking at my first photo the buildings in the foreground are falling inward.

 

[MCTuomey]

I think that's because your photo was taken with the camera leaning forward (lens' axis pointing down).

 

[ampguy]

What I've found is that in nature, it's pretty easy to compose with the CV 21/4, (and, while harder, even the CV 15/4.5) even though some of the distortions mentioned are still present, if you compared with say a 35 cron asph or good 50 on a tripod. The photos can still look pleasing:

But, with square and rectangular architecture, with wider than some 35s, you sometimes have to pick 2 or 3 sides of the square or rectangle, that you wish to be parallel with your frameline edges. For this image, I bracketed, but ended up liking the street, and sky, and right hand side parallel to the print edges, while the left edge of the subject building is converging. I have other images that retained the left side's known vertical perspective, but at the expense of skewing the top, bottom, or right:

The CV lenses do have a bit of barrel distortion, noticeable at the edges, but not severe, and most lenses in the price range would exhibit the same, with the exceptions of some older '70s SLR glass that is not available anymore, and much larger in size.

 

[helen.HH]

To My 'EYE' , All the shots here have a varying
Degree of Heightened Proportions.... thats why 21's are Stellar

Cheers & Thank You my Rff buddies /Bill, Chris, BigEye, Barnwulf
for the Kind Comments...😎

 

[sepiareverb]

I guess I Love Imperfections....

WOW! Such light. Delightful.

 

[tlitody]

Interesting how the buildings are leaning to the left on the left side of the picture and as you look to the right the buildings by the park are leaning to the right.

Looking at my first photo the buildings in the foreground are falling inward.

if film plane is tilted forward from vertical the result is diverging verticals. If film plane is tilted backwards from vertical the result is converging verticals. In this case camera is tilted forwards. Everything to left of centre leans left and everything to right of centre leans right. The reverse is the case if camera is tilting upwards. You can play with that knowledge to get some really extreme effects.

 

[Chris101]

This is from my CV 21/4 on the M8. I am sure there is some distorsion but I cant really see it. As long I I keep the lens level it works like a champ.
http://farm5.static.flickr.com/4146/5443803696_667bc74335_b.jpg

I'm tempted to say that I can't see the distortion for the trees.

 

[tlitody]

Apologies if this is OT, but I found your post interesting.

What happens when you've got the camera level and the framing "correct" and you find yourself with a whole lot of street/parking lot/other in the foreground that's unwanted? You can change lenses. You can crop later. Or, if you have movements you can shift upward and eliminate the unwanted foreground in a few seconds.

Ok, one doesn't "need" a view camera. Just saying there's very often a lot of value in a view camera's movements which is why I like my 35mm T-S lenses a lot.

If your framing is correct you can't shift the lens without changing the framing. So what you are suggesting is taking a different picture without the distractions in it. But you can't have it both ways.
Yes crop out what you don't want. And a lot of photographers will put their tripod on top of their car to remove that close up foreground. And there are telescopic poles you can mount your camera on to get some height to give a better viewpoint. Or use a step ladder. Or yes you can buy a view camera if you want the additional level of difficulty. All I'm saying is that there is often a simpler way of resolving compositional problems which don't involve going to a view camera. Or you can just tilt the camera and enjoy the converging/diverging verticals for their effect.

 

[ampguy]

Hi Chris

Hi Chris

In nature shots, it's hard to know if a tree is really straight or not.

But with buildings and window frames, sometimes chairs or rectangular desks and tables, we assume they might be straight, and can often see the slight effects of barrel distortion.

A common explanation, usually from owners with a bunch of barrel distorted lenses, is that if you are going to shoot architecture, you shouldn't be using a rangefinder or cheap glass. But in the 21st century we live in, it's hard to find a lot of scenes without some known straight lines ...

I'm tempted to say that I can't see the distortion for the trees.

 

[tlitody]

In nature shots, it's hard to know if a tree is really straight or not.

But with buildings and window frames, sometimes chairs or rectangular desks and tables, we assume they might be straight, and can often see the slight effects of barrel distortion.

A common explanation, usually from owners with a bunch of barrel distorted lenses, is that if you are going to shoot architecture, you shouldn't be using a rangefinder or cheap glass. But in the 21st century we live in, it's hard to find a lot of scenes without some known straight lines ...

funny thing is that some biogons such as the Zeiss ZM C Biogon 21 F4.5 or 35 F2 exhibit virtually zero distortion which is less than most other lenses.

 

[ampguy]

right

right

but those are costlier than say a cv 35/2.5 which has very low distortion, and don't have hipster qualities like the hexar af lens :angel:

funny thing is that some biogons such as the Zeiss ZM C Biogon 21 F4.5 or 35 F2 exhibit virtually zero distortion which is less than most other lenses.

 

[MCTuomey]

If your framing is correct you can't shift the lens without changing the framing. So what you are suggesting is taking a different picture without the distractions in it. But you can't have it both ways.
Yes crop out what you don't want. And a lot of photographers will put their tripod on top of their car to remove that close up foreground. And there are telescopic poles you can mount your camera on to get some height to give a better viewpoint. Or use a step ladder. Or yes you can buy a view camera if you want the additional level of difficulty. All I'm saying is that there is often a simpler way of resolving compositional problems which don't involve going to a view camera. Or you can just tilt the camera and enjoy the converging/diverging verticals for their effect.

I applied quotation marks to the term correct in my earlier post to indicate that, hypothetically, the framing wasn't actually correct but had problems needing correction. I should have been clearer, sorry.

I guess I think it's safer & simpler to carry a tilt-shift lens (or even a view camera) than resorting to telescopic poles, step ladders, upper floors in nearby buildings, stilts, stage heels, what-have-you. How do you fit that stuff in your domke anyway?

Anyway, imho, converging/diverging verticals and distortion can work really well - Helen's pics are wunnerful - but they aren't always pleasing.

 

[PKR]

This is what I use when necessary.
http://www.kirkphoto.com/Bubble_Level.html

pkr

 

[tlitody]

I guess I think it's safer & simpler to carry a tilt-shift lens (or even a view camera) than resorting to telescopic poles, step ladders, upper floors in nearby buildings, stilts, stage heels, what-have-you. How do you fit that stuff in your domke anyway?

A tilt shift lens is an easy option for 35mm photography like tilting the camera up or down is. A view camera is not an easy option and requires a whole new system with lenses, a means to develop and scan/print.
Then if you have ever looked at the MTF charts for lens you find that distortion kicks in the further from the lens axis you move meaning there is usually very limited shift without distortion unless you have long focal length lenses with much bigger image circles than your film format. But that means longer focal lengths which means being further from sibject which introduces more foreground which can be problematic. And shift introduces abberations such as coma. With a TS lens for a 35mm camera how much shift do you get without introducing distortion. The (now old) contax 35mm F2.8 shift lens gave 2% distortion in the corners before any shift. I suspect the even shorter lenses available give even more. So use your TS lens to stop converging / diveging verticals but introduce more distortion.😕
I still say the optimum is to place yourself in the optimum position with a distortion free lens. But that is for absolute optimum which architectural photographers may want. Most of us don't need that level of correction as no one really worries about a tad of distortion or converging verticals unless it contains people/faces.

p.s. It's all fairly academic now that you can easily correct distortion and perspective digitally. Only if you are wet printing does it still bear some consideration.

 

[wjlapier]

This is what I use when necessary.
http://www.kirkphoto.com/Bubble_Level.html

pkr

I have one of those but wouldn't think to use it on a RFer. Though, I have to admit I did mount it next to the 21/25 VFer on my IF. But didn't go out shooting with it.

 

[Rob-F]

What I've found is that in nature, it's pretty easy to compose with the CV 21/4, (and, while harder, even the CV 15/4.5) even though some of the distortions mentioned are still present, if you compared with say a 35 cron asph or good 50 on a tripod. The photos can still look pleasing:

But, with square and rectangular architecture, with wider than some 35s, you sometimes have to pick 2 or 3 sides of the square or rectangle, that you wish to be parallel with your frameline edges. For this image, I bracketed, but ended up liking the street, and sky, and right hand side parallel to the print edges, while the left edge of the subject building is converging. I have other images that retained the left side's known vertical perspective, but at the expense of skewing the top, bottom, or right:

The CV lenses do have a bit of barrel distortion, noticeable at the edges, but not severe, and most lenses in the price range would exhibit the same, with the exceptions of some older '70s SLR glass that is not available anymore, and much larger in size.

Ampguy: I wanted to show a method of fixing this problem that I use frequently. I use the perspective correction feature of Photoshop Elements. I'm using PSE 6 currently, since it runs on the iMac.

To do this, I first brought the picture into PSE 6. Then I clicked "new layer from background." Next, I used the perspective feature to widen out the top of the building, straightening the verticals in the process. I rotated the picture slightly clockwise, as the camera was not quite level. Finally, I used the clone stamp to fix blank areas that were created by the rotation.

I'm a stickler for correct verticals, so I also use 28mm and 35mm PC lenses on film and digital Nikons.

Another good trick is to use a wider lens, and hold it in portrait position so as to be able to include the top of the building, while keeping the back (film or sensor plane) vertical. Then you can either crop out the excess foreground, or keep it if it is interesting. I'm finding that a photo of a tall structure often needs some extra foreground; it seems to visually "balance" the height of the building. (This might just be me, though.)

I had to reduce the file size to make it upload, so it will not really be useable to print, but I hope it's good enough to show the basic idea.

Hope this gives you a useful idea or two.

Best, Rob

 

[ferider]

Something I never really paid much attention too, until I saw it in some of my pictures. Distortion. I'll include two pics below, but I'm now curious and wondering about something. Do all 21mm lenses display this much distortion? I don't shoot this wide usually. Any other 21's better at handling distortion? BTW, lens is CV 21/4 LTM. I was using my IF with CV 21/25 finder.

You can test for optical/rectilinear distortion by overlaying straight lines in PS. Like this:

Basically, in your pics, there is none. You don't need another lens 🙂

Roland.

 

[ferider]

Here is an example of barrel distortion (Summilux 50/1.4 v2):

Easy to correct in PS though:

 

[ferider]

Here you see what Roger calls "true wide-angle distortion" (using a 15mm, a fairly rectilinear lens).

Look at the guy on the right (my father in law). This photo made me stop using anything wider than 28.

Roland.